This application is the national phase under 35 U.S.C. xc2xa7 371 of PCT International Application No. PCT/JP99/00279 which has an International filing date of Jan. 26, 1999, which designated the United States of America.
1. Technical Field
The present invention relates to a thermoplastic elastomer composition powder, a powder molding process using said composition powder, and a molded article obtained by powder molding thereof. More specifically, the present invention relates to a thermoplastic elastomer composition powder obtained by blending a pulverized product of a thermoplastic elastomer composition containing a polyolefin-based resin and a rubbery polymer as essential components with a specific amount of a specific fine powder, wherein said composition powder is capable of producing a complicated shape molded article without causing underfill, pinholes, etc., excellent in powder flow property and provides a molded article which is hardly whitened on bending; a powder molding process using said powder; and a molded article obtained by using said powder.
2. Background Arts
Hitherto, a sheet-like molded article having a complicated uneven patterns such as leather grain, stitching and the like on its surface has been used as a skin material of automobile interior parts or the like.
As such molded articles, a molded article which is obtained by powder molding a powder obtained by pulverizing an olefin-based thermoplastic elastomer has been proposed as a substitute for the conventional molded article of a polyvinyl chloride-based resin (for example, refer to Japanese Patent Publication (Kokai) Nos. Hei 5-1183 and 5-5050). However, since the powder prepared by pulverizing such-thermoplastic elastomer had an insufficient powder flowability, it happened to cause problems that when a complicated shape molded article, for example, a molded article having a narrow and high convex part or the like is produced, underfill, pinholes and the like are generated.
Furthermore, in case of producing a molded article with a complicated shape, there have been problems that a molded article obtained by powder molding the powder prepared by pulverizing such thermoplastic elastomer, happens to be whitened on bending, and when said molded article is released from a mold or pre-formed into a predetermined shape before adhering said molded article on a substance material, the bent portion of said molded article tends to be whitened.
The objective of the present invention is to provide a thermoplastic elastomer composition powder obtained by blending a pulverized product of a thermoplastic elastomer composition containing a polyolefin-based resin and a rubbery polymer as essential components with a specific amount of a specific fine powder, wherein said composition powder is capable of producing a complicated shape molded article without causing underfill, pinholes, etc., excellent in powder flow property and provides a molded article which is hardly whitened on bending; a powder molding process using said powder; and a molded article obtained by using said powder.
Namely, the first invention of the present invention relates to a thermoplastic elastomer composition powder obtained by blending a thermoplastic elastomer composition comprising 10 to 250 parts by weight of (b) per 100 parts by weight of (a) described below, having a complex dynamic viscosity xcex7* (1) of 1.5xc3x97105 poise or less and a Newtonian viscosity index n of 0.67 or less with 0.1 to 5 parts by weight of (c) described below per 100 parts by weight of a pulverized product of said thermoplastic elastomer composition.
(a): a polyolefin-based resin,
(b): a rubbery polymer imparting a new single tan xcex4 peak at a temperature different from that of the tan xcex4 peak of (a) and that of the tan xcex4 peak of (b) within the range of xe2x88x9270 to 30xc2x0 C. in a temperature dependence curve of tan xcex4 determined by solid viscoelasticity measurement of the composition obtained by kneading with (a), and
(c): a fine powder having a primary particle diameter of 300 nm or less.
And, the second invention relates to a thermoplastic elastomer composition powder obtained by blending a pulverized product of a thermoplastic elastomer composition comprising a pigment (d) in addition to the fore-mentioned (a) and (b) with (c) described above. The solvent resistance of a molded article prepared by addition of the pigment (d) is improved.
Further, the third invention relates to a powder molding process using the thermoplastic elastomer composition powder of the fore-mentioned first invention or the fore-mentioned second invention.
Further, the fourth invention relates to a molded article obtained by powder molding the thermoplastic elastomer composition powder of the fore-mentioned first invention or the fore-mentioned second invention.